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Groovy: A powerful, dynamic language for the JVM
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/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.codehaus.groovy.tools.ast

import groovy.transform.PackageScope
import org.codehaus.groovy.ast.ClassNode
import org.codehaus.groovy.classgen.GeneratorContext
import org.codehaus.groovy.control.CompilationUnit
import org.codehaus.groovy.control.CompilePhase
import org.codehaus.groovy.control.CompilerConfiguration
import org.codehaus.groovy.control.SourceUnit
import org.codehaus.groovy.transform.ASTTransformation

import java.security.CodeSource

/**
 * This TestHarness exists so that a global transform can be run without
 * using the Jar services mechanism, which requires building a jar.
 *
 * To use this simply create an instance of TransformTestHelper with
 * an ASTTransformation and CompilePhase, then invoke parse(File) or
 * parse(String).
 *
 * This test harness is not exactly the same as executing a global transformation
 * but can greatly aide in debugging and testing a transform. You should still
 * test your global transformation when packaged as a jar service before
 * releasing it.
 */
class TransformTestHelper {

    private final ASTTransformation transform
    private final CompilePhase phase

    /**
     * Creates the test helper.
     * @param transform
     *      the transform to run when compiling the file later
     * @param phase
     *      the phase to run the transform in 
     */
    TransformTestHelper(ASTTransformation transform, CompilePhase phase) {
        this.transform = transform
        this.phase = phase
    }

    /**
     * Compiles the File into a Class applying the transform specified in the constructor.
     * @input input*      must be a groovy source file
     */
    Class parse(File input) {
        TestHarnessClassLoader loader = new TestHarnessClassLoader(transform, phase)
        loader.parseClass(input)
    }

    /**
     * Compiles the String into a Class applying the transform specified in the constructor.
     * @input input*      must be a valid groovy source string
     */
    Class parse(String input) {
        TestHarnessClassLoader loader = new TestHarnessClassLoader(transform, phase)
        loader.parseClass(input)
    }
}

/**
 * ClassLoader exists so that TestHarnessOperation can be wired into the compile.
 */
@PackageScope
class TestHarnessClassLoader extends GroovyClassLoader {

    private final ASTTransformation transform
    private final CompilePhase phase

    TestHarnessClassLoader(ASTTransformation transform, CompilePhase phase) {
        this.transform = transform
        this.phase = phase
    }

    protected CompilationUnit createCompilationUnit(CompilerConfiguration config, CodeSource codeSource) {
        CompilationUnit cu = super.createCompilationUnit(config, codeSource)
        cu.addPhaseOperation(new TestHarnessOperation(transform), phase.phaseNumber)
        cu
    }
}

/**
 * Operation exists so that an AstTransformation can be run against the SourceUnit.
 */
@PackageScope
class TestHarnessOperation implements CompilationUnit.IPrimaryClassNodeOperation {

    private final ASTTransformation transform

    TestHarnessOperation(ASTTransformation transform) {
        this.transform = transform
    }

    @Override
    void call(SourceUnit source, GeneratorContext ignoredContext, ClassNode ignoredNode) {
        this.transform.visit(null, source)
    }
}